Victor K. Lee

Tumor-specific idiotopes on suppressor factors and suppressor cells revealed by monoclonal anti-idiotope antibodies

Two monoclonal anti-idiotope antibodies, previously found to induce tumor-specific cell-mediated immunity in mice, were examined for their relationship to tumor-associated suppressor factors (SF), produced in culture by spleen cells from tumor-bearing mice or present in sera from such mice. A leukocyte adherence inhibition assay was used to detect cellular immunoreactivity to tumor antigens and its inhibition by SF, using peritoneal cells from mice bearing tumor or sensitized with anti-idiotope antibody. The SF were specifically absorbed by the corresponding anti-idiotope antibodies coupled to a solid phase and were recovered by elution. They were also specifically neutralized by the addition of the respective antibodies to the assay system. Anti-idiotope antibody, used with complement to pretreat spleen cells from tumor-bearing mice, prevented these cells from producing SF in culture. Tumor antigen-reactive effector cells, suppressor cells, and SF thus share similar idiotopes, permitting their respective functions to be modulated by appropriate anti-idiotopes.

Anti-idiotypes and cancer therapy

Abstract Anti-idiotypic antibodies 2 (Ab2) relating to tumor-associated differentiation antigens are of interest as therapeutic vaccines, since they may induce or modify a host response to a growing neoplasm. Regressions of small established tumors have been observed in animals treated with Ab2. Furthermore, it has been speculated that the induction of Ab2 in patients treated with antitumor antibodies correlates with a favorable prognosis. Many questions remain to be answered, however, since treatment of experimental tumors with Ab2 is often not very effective and can sometimes even facilitate tumor growth.